Test components using their lowest possible deps

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | not sure
| Fixed tickets | -
| License       | MIT
| Doc PR        | -

Once https://github.com/composer/composer/pull/3450 is merged, we'll see if our deps are correct, and ensure that is kept over time by testing each component with its lowest possible deps versions.